/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1980, 1986, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/boottrace.h>
#include <sys/reboot.h>
#include <sys/sysctl.h>
#include <sys/time.h>

#include <signal.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <syslog.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <utmpx.h>

static void usage(void) __dead2;
static uint64_t get_pageins(void);

static int dohalt;

int
main(int argc, char *argv[])
{
	struct utmpx utx;
	const struct passwd *pw;
	int ch, howto, i, fd, lflag, nflag, qflag, sverrno, Nflag;
	uint64_t pageins;
	const char *user, *kernel = NULL;

	if (strstr(getprogname(), "halt") != NULL) {
		dohalt = 1;
		howto = RB_HALT;
	} else
		howto = 0;
	lflag = nflag = qflag = Nflag = 0;
	while ((ch = getopt(argc, argv, "cdk:lNnpqr")) != -1)
		switch(ch) {
		case 'c':
			howto |= RB_POWERCYCLE;
			break;
		case 'd':
			howto |= RB_DUMP;
			break;
		case 'k':
			kernel = optarg;
			break;
		case 'l':
			lflag = 1;
			break;
		case 'n':
			nflag = 1;
			howto |= RB_NOSYNC;
			break;
		case 'N':
			nflag = 1;
			Nflag = 1;
			break;
		case 'p':
			howto |= RB_POWEROFF;
			break;
		case 'q':
			qflag = 1;
			break;
		case 'r':
			howto |= RB_REROOT;
			break;
		case '?':
		default:
			usage();
		}
	argc -= optind;
	argv += optind;
	if (argc != 0)
		usage();

	if ((howto & (RB_DUMP | RB_HALT)) == (RB_DUMP | RB_HALT))
		errx(1, "cannot dump (-d) when halting; must reboot instead");
	if (Nflag && (howto & RB_NOSYNC) != 0)
		errx(1, "-N cannot be used with -n");
	if ((howto & RB_POWEROFF) && (howto & RB_POWERCYCLE))
		errx(1, "-c and -p cannot be used together");
	if ((howto & RB_REROOT) != 0 && howto != RB_REROOT)
		errx(1, "-r cannot be used with -c, -d, -n, or -p");
	if (geteuid()) {
		errno = EPERM;
		err(1, NULL);
	}

	if (qflag) {
		reboot(howto);
		err(1, NULL);
	}

	if (kernel != NULL) {
		fd = open("/boot/nextboot.conf", O_WRONLY | O_CREAT | O_TRUNC,
		    0444);
		if (fd > -1) {
			(void)write(fd, "nextboot_enable=\"YES\"\n", 22);
			(void)write(fd, "kernel=\"", 8L);
			(void)write(fd, kernel, strlen(kernel));
			(void)write(fd, "\"\n", 2);
			close(fd);
		}
	}

	/* Log the reboot. */
	if (!lflag)  {
		if ((user = getlogin()) == NULL)
			user = (pw = getpwuid(getuid())) ?
			    pw->pw_name : "???";
		if (dohalt) {
			openlog("halt", 0, LOG_AUTH | LOG_CONS);
			syslog(LOG_CRIT, "halted by %s", user);
		} else if (howto & RB_REROOT) {
			openlog("reroot", 0, LOG_AUTH | LOG_CONS);
			syslog(LOG_CRIT, "rerooted by %s", user);
		} else if (howto & RB_POWEROFF) {
			openlog("reboot", 0, LOG_AUTH | LOG_CONS);
			syslog(LOG_CRIT, "powered off by %s", user);
		} else if (howto & RB_POWERCYCLE) {
			openlog("reboot", 0, LOG_AUTH | LOG_CONS);
			syslog(LOG_CRIT, "power cycled by %s", user);
		} else {
			openlog("reboot", 0, LOG_AUTH | LOG_CONS);
			syslog(LOG_CRIT, "rebooted by %s", user);
		}
	}
	utx.ut_type = SHUTDOWN_TIME;
	gettimeofday(&utx.ut_tv, NULL);
	pututxline(&utx);

	/*
	 * Do a sync early on, so disks start transfers while we're off
	 * killing processes.  Don't worry about writes done before the
	 * processes die, the reboot system call syncs the disks.
	 */
	if (!nflag)
		sync();

	/*
	 * Ignore signals that we can get as a result of killing
	 * parents, group leaders, etc.
	 */
	(void)signal(SIGHUP,  SIG_IGN);
	(void)signal(SIGINT,  SIG_IGN);
	(void)signal(SIGQUIT, SIG_IGN);
	(void)signal(SIGTERM, SIG_IGN);
	(void)signal(SIGTSTP, SIG_IGN);

	/*
	 * If we're running in a pipeline, we don't want to die
	 * after killing whatever we're writing to.
	 */
	(void)signal(SIGPIPE, SIG_IGN);

	/*
	 * Only init(8) can perform rerooting.
	 */
	if (howto & RB_REROOT) {
		if (kill(1, SIGEMT) == -1)
			err(1, "SIGEMT init");

		return (0);
	}

	/* Just stop init -- if we fail, we'll restart it. */
	BOOTTRACE("SIGTSTP to init(8)...");
	if (kill(1, SIGTSTP) == -1)
		err(1, "SIGTSTP init");

	/* Send a SIGTERM first, a chance to save the buffers. */
	BOOTTRACE("SIGTERM to all other processes...");
	if (kill(-1, SIGTERM) == -1 && errno != ESRCH)
		err(1, "SIGTERM processes");

	/*
	 * After the processes receive the signal, start the rest of the
	 * buffers on their way.  Wait 5 seconds between the SIGTERM and
	 * the SIGKILL to give everybody a chance. If there is a lot of
	 * paging activity then wait longer, up to a maximum of approx
	 * 60 seconds.
	 */
	sleep(2);
	for (i = 0; i < 20; i++) {
		pageins = get_pageins();
		if (!nflag)
			sync();
		sleep(3);
		if (get_pageins() == pageins)
			break;
	}

	for (i = 1;; ++i) {
		BOOTTRACE("SIGKILL to all other processes(%d)...", i);
		if (kill(-1, SIGKILL) == -1) {
			if (errno == ESRCH)
				break;
			goto restart;
		}
		if (i > 5) {
			(void)fprintf(stderr,
			    "WARNING: some process(es) wouldn't die\n");
			break;
		}
		(void)sleep(2 * i);
	}

	reboot(howto);
	/* FALLTHROUGH */

restart:
	BOOTTRACE("SIGHUP to init(8)...");
	sverrno = errno;
	errx(1, "%s%s", kill(1, SIGHUP) == -1 ? "(can't restart init): " : "",
	    strerror(sverrno));
	/* NOTREACHED */
}

static void
usage(void)
{

	(void)fprintf(stderr, dohalt ?
	    "usage: halt [-clNnpq] [-k kernel]\n" :
	    "usage: reboot [-cdlNnpqr] [-k kernel]\n");
	exit(1);
}

static uint64_t
get_pageins(void)
{
	uint64_t pageins;
	size_t len;

	len = sizeof(pageins);
	if (sysctlbyname("vm.stats.vm.v_swappgsin", &pageins, &len, NULL, 0)
	    != 0) {
		warn("v_swappgsin");
		return (0);
	}
	return (pageins);
}